I was swimming in a pool seeing how long I could stay under without coming up.  I did the same thing each day for a month.  Know I am swimming with the fish non-stop, having an underwater party and showing my abilities to an audience thinking I’m great.  If you look at me now, I can stay under for one hour in the sea, a fish tank, a pool even a bath that is how I can stay under water for one hour. I bet with allot of practice you can do it to if you wanted.